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n. The difference in phase shift between two characteristic polarizations of light upon reflection from an interface. Retardance can be reported in the Abelès or Mueller conventions. The retardance phase shift angle is often specified in degrees.

n. A numerical constant, proportional to the capacity and resistance of a telephone-line, which gives the maximum distance over which speech may be successfully transmitted.

"They increase the time constant and introduce a slowness which may be called retardance, for they diminish the rate at which currents can be transmitted."